WorkFront Preview: Calculated Field Error

In Preview, I am trying to adjust equations in a calculated field, after I click Done in the field editor clicking "Apply" results in this error. I am using the exact field names and WorkFront is even auto filling them. Why won't it take my changes?

• ROI Final
  • calculation: SUB(ROI A2 for GP, ROI_B for GPG)
  • Forma: Currency
• ROI A2 for GP
  • calculation: (ROI Cost Reduction+ROI New Revenue)+ROI Risk Loss of Revenue
  • Format: Number
• ROI_B for GPG
  • calculation: PROD(Planned Hours,65)/60
  • Format: Currency

This is very frustrating since it feels like anytime I need to make updates to a calculated field something makes it take twice as long as it feels like it should